Metrics

Part of Session Insights — live O(1) reducers over public events: session duration, focus/hidden/idle/sleep time, counts, and attention score. In-process session understanding, not a product analytics SDK.

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Timeline not required

Metrics never scans Timeline history (ADR A6).

Import path

import { createBrowserLifecycle, createMetricsApi } from "@jayoncode/browser-lifecycle";

Usage

import { createBrowserLifecycle, createMetricsApi } from "@jayoncode/browser-lifecycle";

const lifecycle = createBrowserLifecycle({ idleTimeout: 30_000 });
const metrics = createMetricsApi(lifecycle);

metrics.sessionDuration();
metrics.focusedDuration();
metrics.hiddenDuration();
metrics.idleDuration();
metrics.sleepDuration();

metrics.attention().score; // 0–100
metrics.stats(); // focus/visibility/idle/reconnect/sleep counts
metrics.snapshot(); // full MetricsSnapshot

metrics.reset();
metrics.dispose();

Attention score

score = round(100 * focusedMs / (focusedMs + blurredMs + hiddenMs))

When the denominator is 0, score is 0.

What it tracks

Durations: session, visible, hidden, focused, blurred, active, idle, online, offline, sleep.

Counts: hidden, visibility changes, focus/blur, idle, reconnect, sleep, primary-tab switches.

Reports →